求证(3-sin^4 x-cos^4 x)/2cos^2 x=1+tan^2 x+sin^2 x

已知tan=2,求(cos x+sin x)/(cos x-sin x)+sin^2x 求证（cos^2 x-sin^2 x)(cos^4 x+sin^4 x)+1/4 sin 2x sin 4x=cos 2 证明(1-2sin x cos x )/(cos^2x-sin^2x)=(1-tan x)/(1+tan x) 三角等式求证：cos^6x+sin^6x=1-3sin^2x+3sin^4x 证明sin^2(x)+cos^2(x+30)+sin(x)cos(x+30)=3/4 化简[1-(sin^4x-sin^2cos^2x+cos^4x)/(sin^2)]+3sin^2x 求证 （1—tan^2X)/(1+tan^2X)=cos^2X—sin^2X 化简sin(3π-x)cos(x-3/2)cos(4π-x)/tan(x-5π)cos(π/2+x)sin(x-5/2π 求证 tan（2π-X）sin（-2π-X）cos（6π-X）/ sin（X+3π/2)*cos（X+3π/2)=-ta 证明1-tan^2x/1+tan^2x=cos^2x-sin^2x (1-(sin^4x-sin^2xcos^2x+cos^4x)/sin^2x +3sin^2x 求导f(x) = cos(3x) * cos(2x) + sin(3x) * sin(2x).